The appetite for custom-built, and self-built houses is growing.

But there's a difference.

Harvey Fremlin, who runs the National Self-Build and Renovation centre in Swindon said: "With self-building, you buy a plot of land and you are responsible for everything else - the house , access, everything. With custom build, typically, a developer will set out the plots and the roads and services, and the houses are then built to custom specifications."

And the most popular element of those specifications is energy efficiency, added Harvey: "We run courses on energy efficiency and heating and they are always the most sold out. Heating bills are only every going to go up

"We always say 'fabric first'. The best thing to do is make sure the house is insulated well before thinking about the other technologies like solar panels or heat pumps. Spend more on the insulation."